Thermostatically-controlled circuit.



J. F. McELROY.

THERMOSTATICALLY CONTROLLED CIRCUIT. APPLICATION FILED NOV-3.1914.

1,270,851. Patented July 2, 1918.

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UNITED STATES PATENT OFFIGEO JAMES F. MCELROY, OF ALBANY, NEW YORK,A-SSIGNOR TO CONSOLIDATED CAR- I-IEATING COMPANY, A CORPORATION OF WESTVIRGINIA.

THERMOSTATICALLY-CONTROLLED CIRCUIT.

Application filed November 3, 1914.

To all whom it may concern Be it known that I, James F. MoELRoY, acitizen of the United States, residing at Albany, county of Albany,State of New York, have invented certain new and useful Improvements inThermostatically-Controlled Circuits, the following being a full, clear,and exact disclosure of the one form of my invention which I at presentdeem preferable,

For a detailed description of the present form of my invention,reference may be had to the following specification and to theaccompanying drawings, which illustrate my invention.

My invention relates to circuits which are under thermostatic control.In particular, I have applied my invention to an electric heatercircuit.

I place in the circuit to be controlled a switch for opening or closingit and provide a magnet which when energized will act to close theswitch, and when deenergized will allow the switch to fall open bygravity or by a spring. This magnet is placed in a branch circuit aroundthe heaters in series therein with a substantial resistance. In a secondbranch circuit which shunts the said magnet I place contacts controlledby a thermostat so that when the temperature rises the thermostat willclose the said contacts and thereby divert sufficient current from thesaid switch-operating magnet to cause it to release its armature therebyopening the heater circuit. Conversely when the temperature falls thethermostat will open the said contacts thereby opening the shunt circuitaround the magnet to cause it to attract its armature and close theheater circuit. It will be observed that the resistance aforesaid is inseries with both the magnet and the thermostat-controlled shuntcircuit.- Hence only a. limited amount of current can flow in eithercircuit which current can be diverted from or restored to the magnetaccording as the thermostat closes or opens its contacts. Moreover thepotential-difference between the contacts can not exceed that which isdetermined by the resistance of the magnet coils, which resistance maybe small by virtue of the high external resistance in series therewith.I am thus able to use this arrangement with circuits of 1200 volts ormore such as have recently come into use on electric railways, it beingmy special pur- Specification of Letters Patent.

Patented July 2, 1918.

Serial No. 870.079.

pose to thus control electric heaters on electric railway cars.

Referring to the drawing, the invention is diagrammatically illustrated,and as shown comprises a magnet M supported upon a suitable base andprovided with means for pivotally supporting a movable switch member Sprovided with a contact C, arranged to cooperate with a stationarycontact C, connected with a blow-out magnet conventionally shown. Themagnet M, or movable switch member, and contacts, may be of anypreferred construction, well known in the art, the said parts beingconventionally shown for the purpose of illustration.

HI-l designate two electric heater sections, included within a circuit,the conductors of which are designated by the numeral 1. The saidcircuit leads from the trolley through a manual switch S, of any desiredconstruction, and from thence through the heater sections to the movablecontact C carried by the blade S and from thence through the blow-outmagnet to ground G, the wires buried in the supporting base beingindicated in dotted lines. Leading from the circuit 1, is a branchcircuit 2 including a resistance R, the circuit wires leading from saidresistance through the supporting base to the magnet M, from thencepreferably to a fuse of any preferred form and from thence to ground G.

A second branch circuit leading from a point between the resistance andthe magnet consists of conductors 3 leading to a thermostatic element Bprovided with movable contact 0 and stationary contact 0, the wires 3leading from the thermostat to ground G, the last mentioned branchcircuit being in parallel with the magnet and in series with theresistance. The thermostat B may be of any preferred construction.

In the drawing the parts are shown with the current passing through thethermostat and shunting both the heaters H and magnet M. When thetemperature drops sufficiently, the branch circuit 3 is broken by thethermostat, and as a consequence the current will pass through branch 2,to the circuit magnet M, thereby effecting an operation of the switchblade S bringing the contacts C C together, thereby causing the circuit1 to pass through the heaters H. When the temperature rises suflicientlyto effect a reverse operation of the thermostat, the branch circuit 3 isclosed, thereby shunting the magnet M and as a consequence the blade Swill drop, breaking the circuit at C, C so that the current will nolonger pass through the heaters H and such current as may pass throughthe magnet will be insufiicient to attract the armature thereof.

What I claim as new and desire to secure by Letters Patent is:

1. An improvement in thermostatically controlled circuits comprisingmeans for providing a heater circuit, an electric heater Within saidcircuit, a switch controlling said circuit, means for providing a branchcircuit from said heater circuit, a magnet permanently in said branchcircuit, an external resistance also in said branch circuit, means forproviding a second branch circuit in parallel with the magnet and inseries with the resistance, and a thermostat controlling the lastmentioned branch circuit.

2. An improvement in thermostatically controlled circuits comprisingmeans for providing a heater circuit, an electric heater within saidcircuit, a switch controlling said circuit, means for providing a branchcircuit from said heater circuit, a magnet permanently in said branchcircuit, an external resistance in said branch circuit in series withsaid magnet, means for providing a second branch circuit in parallelwith said magnet and in series with the resistance, and a thermostat forcontrolling the last mentioned branch circuit.

In witness whereof I have hereunto set my hand, before two subscribingwitnesses, this21st day of October, 1914.

JAMES F. MGELROY.

lVitnesses:

HERBERT A. CALKINs, FREDK. C. MANNING.

Games e! thin patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

' Washington, D. C.

